let huan = 
let obj = {
	num: 10,
	huan: obj
};

function deepCopy (obj) {
	let result = {};
	for(let key in obj){
		let item = obj[key];
		if(typeof item === 'object' || typeof item === 'array'){
			result[key] = deepCopy(item);
		}else{
			result[key] = item;
		}
	}
	return result;
}
console.log(deepCopy(obj));